1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_TRACE_SEQ_H
3 #define _LINUX_TRACE_SEQ_H
4
5 #include <linux/seq_buf.h>
6
7 #include <asm/page.h>
8
9 /*
10 * Trace sequences are used to allow a function to call several other functions
11 * to create a string of data to use.
12 *
13 * Have the trace seq to be 8K which is typically PAGE_SIZE * 2 on
14 * most architectures. The TRACE_SEQ_BUFFER_SIZE (which is
15 * TRACE_SEQ_SIZE minus the other fields of trace_seq), is the
16 * max size the output of a trace event may be.
17 */
18
19 #define TRACE_SEQ_SIZE 8192
20 #define TRACE_SEQ_BUFFER_SIZE (TRACE_SEQ_SIZE - \
21 (sizeof(struct seq_buf) + sizeof(size_t) + sizeof(int)))
22
23 struct trace_seq {
24 char buffer[TRACE_SEQ_BUFFER_SIZE];
25 struct seq_buf seq;
26 size_t readpos;
27 int full;
28 };
29
30 static inline void
31 trace_seq_init(struct trace_seq *s)
32 {
33 seq_buf_init(&s->seq, s->buffer, TRACE_SEQ_BUFFER_SIZE);
34 s->full = 0;
35 s->readpos = 0;
36 }
37
38 /**
39 * trace_seq_used - amount of actual data written to buffer
40 * @s: trace sequence descriptor
41 *
42 * Returns the amount of data written to the buffer.
43 *
44 * IMPORTANT!
45 *
46 * Use this instead of @s->seq.len if you need to pass the amount
47 * of data from the buffer to another buffer (userspace, or what not).
48 * The @s->seq.len on overflow is bigger than the buffer size and
49 * using it can cause access to undefined memory.
50 */
51 static inline int trace_seq_used(struct trace_seq *s)
52 {
53 return seq_buf_used(&s->seq);
54 }
55
56 /**
57 * trace_seq_buffer_ptr - return pointer to next location in buffer
58 * @s: trace sequence descriptor
59 *
60 * Returns the pointer to the buffer where the next write to
61 * the buffer will happen. This is useful to save the location
62 * that is about to be written to and then return the result
63 * of that write.
64 */
65 static inline char *
66 trace_seq_buffer_ptr(struct trace_seq *s)
67 {
68 return s->buffer + seq_buf_used(&s->seq);
69 }
70
71 /**
72 * trace_seq_has_overflowed - return true if the trace_seq took too much
73 * @s: trace sequence descriptor
74 *
75 * Returns true if too much data was added to the trace_seq and it is
76 * now full and will not take anymore.
77 */
78 static inline bool trace_seq_has_overflowed(struct trace_seq *s)
79 {
80 return s->full || seq_buf_has_overflowed(&s->seq);
81 }
82
83 /*
84 * Currently only defined when tracing is enabled.
85 */
86 #ifdef CONFIG_TRACING
87 extern __printf(2, 3)
88 void trace_seq_printf(struct trace_seq *s, const char *fmt, ...);
89 extern __printf(2, 0)
90 void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args);
91 extern void
92 trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary);
93 extern int trace_print_seq(struct seq_file *m, struct trace_seq *s);
94 extern int trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
95 int cnt);
96 extern void trace_seq_puts(struct trace_seq *s, const char *str);
97 extern void trace_seq_putc(struct trace_seq *s, unsigned char c);
98 extern void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len);
99 extern void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
100 unsigned int len);
101 extern int trace_seq_path(struct trace_seq *s, const struct path *path);
102
103 extern void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
104 int nmaskbits);
105
106 extern int trace_seq_hex_dump(struct trace_seq *s, const char *prefix_str,
107 int prefix_type, int rowsize, int groupsize,
108 const void *buf, size_t len, bool ascii);
109 char *trace_seq_acquire(struct trace_seq *s, unsigned int len);
110
111 #else /* CONFIG_TRACING */
112 static inline __printf(2, 3)
113 void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
114 {
115 }
116 static inline void
117 trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
118 {
119 }
120
121 static inline void
122 trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
123 int nmaskbits)
124 {
125 }
126
127 static inline int trace_print_seq(struct seq_file *m, struct trace_seq *s)
128 {
129 return 0;
130 }
131 static inline int trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
132 int cnt)
133 {
134 return 0;
135 }
136 static inline void trace_seq_puts(struct trace_seq *s, const char *str)
137 {
138 }
139 static inline void trace_seq_putc(struct trace_seq *s, unsigned char c)
140 {
141 }
142 static inline void
143 trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len)
144 {
145 }
146 static inline void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
147 unsigned int len)
148 {
149 }
150 static inline int trace_seq_path(struct trace_seq *s, const struct path *path)
151 {
152 return 0;
153 }
154 static inline char *trace_seq_acquire(struct trace_seq *s, unsigned int len)
155 {
156 return NULL;
157 }
158 #endif /* CONFIG_TRACING */
159
160 #endif /* _LINUX_TRACE_SEQ_H */
161
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